Participation of the Escherichia coli heat shock proteins DnaJ, DnaK, and GrpE in autorepression of the P1 plasmid repA promoter.
The replicon of the low copy number plasmid P1 uses the three Escherichia coli heat shock proteins DnaJ, DnaK, and GrpE for the efficient initiation of its DNA replication. The only P1-encoded protein required for plasmid replication is the initiator, RepA. Binding of RepA to the origin also represses the promoter for the repA gene, which is located within the origin. We found that repression is incomplete in E. coli strains with mutations in the dnaJ, dnaK, or grpE genes. Since there is no decrease in RepA concentration in the mutant strains, the mutations are likely to affect the protein-DNA or protein-protein reactions required for repression, thereby decreasing RepA binding at its promoter. We also showed that the deficit in repression can be overcome by providing excess RepA, implying that the mechanism of repression is not altered in the mutant strains. Since repression requires RepA binding to the origin, a binding deficit might account for the replication defect in the heat shock mutants.
Tilly
K
K
National Cancer Institute, Laboratory of Biochemistry, National Institutes of Health, Bethesda, MD 20892.
Sozhamannan
S
S
Yarmolinsky
M
M
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004265:DNA Helicases; D004261:DNA Replication / Q000235:genetics; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D005809:Genes, Regulator; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D009154:Mutation; D010957:Plasmids; D011401:Promoter Regions, Genetic; D011506:Proteins; D015534:Trans-Activators
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D011506:Proteins; D015534:Trans-Activators; C045264:replication initiator protein; D004265:DNA Helicases